mg_disk: remove prohibited sleep operation

mflash's polling driver operate in standard request_fn_proc's context,
sleep in this isn't permitted.
Signed-off-by: unsik Kim <donari75@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

drivers/block/mg_disk.c

@@ -245,8 +245,6 @@ static unsigned int mg_wait(struct mg_host *host, u32 expect, u32 msec)
 			mg_dump_status("not ready", status, host);
 			return MG_ERR_INV_STAT;
 		}
-		if (prv_data->use_polling)
-			msleep(1);
 
 		status = inb((unsigned long)host->dev_base + MG_REG_STATUS);
 	} while (time_before(cur_jiffies, expire));